Carrier aggregation technology is introduced in the Long Term Evolution-Advanced (LTE-Advanced) system, and aggregating two or more basic carriers, it meets the bandwidth requirement for the LTE-Advance system. In carrier aggregation, each User Equipment (UE) may be assigned with multiple carrier components (CCs), which are used for communication with large data load.
When a Secondary Component Carrier (SCC) is activated, the UE will transmit a Sounding Reference Symbol (SRS) and report a Channel Quality Indicator/Precoding Matrix Indicator/Rank Indicator (CQI/PMI/RI) in a Secondary Cell (SCell) according to the configuration. The UE will also monitor the Physical Downlink Control Channel (PDCCH) in the SCell. When the data load of the UE is not heavy and the SCC is not required, the UE will nonetheless perform blind detection, which consumes the power to the UE and lowers the efficiency. In this condition, it requires to deactivate the SCC.
Specifically, after the SCC is deactivated, the UE will:                (1) stop transmitting the SRS in the SCell;        (2) stop reporting the CQI/PMI/RI in the SCell;        (3) stop sending the Physical Uplink Shared Channel (PUSCH) in the SCell;        (4) stop monitoring the PDCCH in the SCell; and        (5) stop monitoring control information of the SCell from the PDCCH over a scheduled carrier during cross-carrier scheduling.        
After the SCC is activated, the UE will:                (1) transmit the SRS in the SCell according to the configuration;        (2) report the CQI/PMI/RI in the SCell according to the configuration;        (3) monitor the PDCCH in the SCell, and receive PUSCH data according to scheduling information; and        (4) monitor control information of the SCell from the PDCCH over a scheduled carrier during cross-carrier scheduling.        
Currently, activation and deactivation actions are performed according to data load per millisecond, therefore it is likely to perform multiple activation and deactivation actions within a short time. Because scheduling of an SCC has to wait until ACK (confirmation) for data packet of a Media Access Control Control Element (MAC CE) is feedback, excessive activation and deactivation actions may influence the velocity stability of the SCC.